THE INTERACTION OF O-2, NO, AND N2O WITH GE SURFACES

The interaction of molecular oxygen (O2), nitric oxide (NO), and nitrous oxide (N2O) with Ge(111), Ge(111) disordered by sputter-etching, and amorphous Ge (a-Ge) surfaces was studied at room temperature using high-resolution electron energy loss spectroscopy (HREELS), core level and valence band EELS, and Auger electron spectroscopy. The interaction of activated NO, N2O, and N2 molecules with these surfaces was also examined. Results indicate that oxygen originating from O2 bonds to surface and subsurface Ge atoms in a bridge configuration. Penetration is more pronounced at the disordered surfaces resulting in a dilute bridge bonding configuration (+ 1 oxidation state), whereas the + 1 to + 3 oxidation states are observed at the similarly treated Ge(111). The N2O molecules decompose to desorbing N2 molecules and chemisorbed oxygen atoms. In contrast, nitrogen and oxygen are detected by Auger analysis at the NO-exposed surfaces. However, the germanium nitride vibrational modes are identified only after heating these surfaces to ~ 550 ° C. A precursor Ge nitride is observed at room temperature following exposure to nitrogen atoms and ions. Only the + 1 oxidation state is observed for the surfaces exposed to NO and N2O. This behavior is discussed and compared to O2 chemisorption. Electronic EELS of Ge surfaces exposed to activated NO, N2O, and N2 indicate that bonding occurs at the surface dangling bonds. Nitrogen related electronic losses are also identified. © 1990.